Bandwidth spiking to 100 percent

[ktravis02]

Hello, in my Cisco Configuration Professional, in Monitor, Router, Interface status, Bandwidth usage graph, I am seeing continuous spikes going from zero to 100 percent. Is this normal, or is my bandwidth getting maxed out and I need to worry about it? See attached graphic.

Thank you,

Ken

[Joseph W. Doherty]

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Posting

It's very possible bandwidth is being maxed out, which is often normal if senders have more bandwidth feeding to the link/path you're measuring.  Whether it's a problem depends on your traffic/application needs.

[ktravis02]

Hi Joseph,

We have customers hitting a website, and udp device traffic incoming and outgoing though a vpn tunnel and the Internet. My concern is that no traffic gets drop. I think it's strange how the traffic is swinging from zero to 100 and back. Any idea how I can verify that I don't need more bandwidth to insure customer and device traffic?

Thanks,

Ken

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Unless you can build a network without any oversubscription, you'll likely to always have some drops.  Traditional TCP, by design, "discovers" available bandwidth by sending traffic, "faster and faster", until there are drops, and then backs off, i.e. slows downs, and repeats the cycle.

What you might do is measure your overall drop rate.  If the drop rate exceeds 1%, then you might try to mitigate the drop rate, often by providing more bandwidth.

There are also some advanced techniques, to try to regulate bandwidth usage, but these generally require special traffic management appliances.

[Rafatur Rahman]

Hello Ken,

Greetings! Yes, it is very much possible the link bandwidth getting maxed out, utilization reaching 100%.

You can take following steps to isolate the issue:

-- Check  the interface utilization. You might need to take a Wireshark capture to isolate the spikes and packet which are causing these spikes.

-- Verify what kind of traffic is passing through this interface.

-- Are all those valid traffic, if yes, then you might need to provision extra bandwidth.

-- If the traffic is not valid, then you might need to isolate the source of that traffic and stop those packets from hitting the interface.

I hope this helps.

Regards,

[ktravis02]

Thank you all for your responses. I think I have figured it out. The bandwidth wasn't set on the dialer Interface, and I believe it defaults to 56k. Once I set the dialer interface it to 4000k, which is suppose to be my DSL up speed things look a bit better.

It is vary confusing configuring a dialer - DSL interface for monitoring, and I can't seem to get a straight answer about what to apply where - the interface or the dialer interface - especially netflow. I had set the bandwidth for the interface and not the dialer.

Ken